A typical rotary engine is composed of three separate metal castings including a central casting that defines an epitrochoidal rotor chamber and a pair of end castings which are mounted on either side of the central casting. Both the central and end castings normally include water cooling passages with the water passages in the three castings being interconnected. In addition, the rotary engine can also include air passages, in which air is introduced into one of the end castings, flows through the rotor chamber of the central casting, and is discharged from the opposite end casting.
It is difficult using conventional sand casting techniques to cast the thin sections for the internal cooling cavities that are required in the rotory engine. Consequently it has been necessary to use core wires and core supports, when producing these sections by sand casting. The core wires must be removed after casting and the use of core supports results in holes being formed in the cast sections, which must be subsequently plugged.
In addition, with sand casting techniques dowel holes and bolt holes cannot be produced in the metal castings, so that these holes must be subsequently drilled in the cast parts. Further, water inlet and outlet openings are not produced in the metal casting and also must be subsequently drilled.